Reducing Substance, Feces
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Testing for fecal reducing substances (carbohydrates) aides in determining the underlying cause of diarrhea. Elevations in fecal reducing substances helps distinguish between osmotic diarrhea caused by abnormal excretion of various sugars as opposed to diarrhea caused by viruses and parasites. Increased reducing substances in stool are consistent with, but not diagnostic of, primary or secondary disaccharidase deficiency (primarily lactase deficiency) or intestinal monosaccharide malabsorption. Similar intestinal absorption deficiencies are associated with short bowel syndrome and necrotizing enterocolitis.
Assisting in the differentiation between osmotic and nonosmotic diarrhea
Screening test for:
-Diarrhea from disaccharidase deficiencies, (eg, lactase deficiency)
Normal: < or =0.25 g/dL (trace)
Suspicious: >0.25 to 0.50 g/dL (grade 1)
Abnormal: >0.50 g/dL (grade 2-4)
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
This test has poor sensitivity for oligosaccharides.
Antibiotics can alter the intestinal flora and affect acid production.
False-positive reactions due to drugs (salicylates, penicillin, ascorbic acid, nalidixic acid, cephalosporins and probenecid) are possible.
Stool may be contaminated with urine, in which case glycosuria will give false-positive results.
Diaper collections can be falsely decreased as the fluid portion containing water soluble sugars is absorbed into the diaper.
Ambient transport temperatures result in growth of bacteria that consume sugars resulting in falsely decreased values. Ambient specimens will be rejected.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Negative or trace
Clinical References Provides recommendations for further in-depth reading of a clinical nature
1. Siddiqui HA, Salwen MJ, Shaikh MF, et al: Laboratory Diagnosis of Gastrointestinal and Pancreatic Disorders. In Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd edition. Elsevier Inc, St. Louis, MO 2017;22:306-323 e2
2. Branski D: Disorders of Malabsorption. In Nelson Textbook of Pediatrics. Edited by RM Kleigman, BF Stanton, JW St. Geme, et al. Elsevier In., Philadelphia, PA, 2016, pp1831-1850.e2
3. Bhatia J, Prihoda AR, Richardson CJ: Parenteral antibiotics and carbohydrate intolerance in term neonates. Am J Dis Child 1986;140:111-113
4. Book LS, Herbst JJ, Jung AL: Carbohydrate malabsorption in necrotizing enterocolitis. Pediatrics 1976;57:201-204
5. Krom FA, Frank CG. Clinitesting neonatal stools. Neonatal Network 1989;8(2):37-40
6. Qualitative Methods for Total Reducing Substances. In Tietz Textbook of Clinical Chemistry, Second Edition. 1994, pp 968-969